You might find records in the 'cmdb_ci' table with discovery source of CredentiallessDiscovery when using ServiceNow's Service Mapping.
There are some identification sections within ServiceNow patterns were the Discovery Source is set to "CredentiallessDiscovery"
For example, if you navigate to Pattern Designer >> Discovery Patterns and search the list for "Apache on Windows Pattern" you will see a Identification Sections. If you click the named "Lightweight Identification for Apache" you will see step 3 is setting the Discovery Source (below)
Similarly, there are many such patterns which have lightweight identification sections where discovery source is set to CredentiallessDiscovery